Albert Teen
powered by
Albert logo


The Heart and Circulation

The Heart and Circulation

The Heart and Circulation

The heart is an organ that allows circulation of blood to take place in the body.

The heart is a muscular organ, responsible for pumping blood around the body. It sends blood to different systems, depending on whether the blood is oxygenated or deoxygenated.

Humans have double circulatory systems. Why do you think our circulatory system is described as "double"?

The two circuits in our bodies are the pulmonary circuit and the systemic circuit.


This is a human heart

First, we will look at its structure, and then we will understand how it functions.


Notice that the left and right labels are on opposite sides.

Imagine you are looking at a real person from the front. These labels show which side of their body the different structures are found.


Fill the gap: The left side of the heart shows the blood in red, because that blood is ____________.


The blood in the right side of the heart is more blue-ish...

because that side deals with deoxygenated blood.


The heart is made up of chambers. How many?


The heart has veins leading into it and arteries leading out of it. Is it veins or arteries that generally carry deoxygenated blood?


We say that arteries "generally" carry oxygenated blood and veins "generally" carry deoxygenated blood, because it is not true for all arteries and veins!

The pulmonary arteries have deoxygenated blood, because they carry blood away from the heart to the lungs to oxygenate the blood again. The pulmonary veins have just come from the lungs, so they carry oxygenated blood back into the heart.


Now, look at the vena cava and the aorta. One of them sends blood to the circulatory system from the heart. The other one returns blood to the heart from the circulatory system. Which one returns blood to the heart?


Look at the picture again. Which of these statements is true?


The left side of the heart muscle is thicker than the right side.

This is because the blood in the left side has to travel to even the furthest corners of the body, so it needs to be sent off with great pressure to get there. That means those heart muscles have to be very strong. The blood in the right side only goes to the lungs, so it doesn't need as much pressure.


So blood flows into the two atria (right atrium and left atrium). Through which veins do they flow into the atria?


The two veins carry different types of blood

The vena cava is carrying deoxygenated blood from the body. The pulmonary vein is carrying oxygenated blood from the lungs.


Next, the atria contract. Where does the blood go next?


The ventricles then contract to push blood out of the heart. Through which type of blood vessels does the blood escape the heart?


The blood from the two sides of the heart does not go to the same place!

The pulmonary artery take deoxygenated blood to the lungs to get oxygenated. The aorta takes oxygenated blood (that has just completed the trip from the lungs) to tissues in the body where cells needs the oxygen for respiration.


What structures can you see that prevent blood from flowing backwards?

A few tips to remember all the heart characteristics


Blood flows into the ATRIA first, then the VENTRICLES

In alphabetic order, A also comes before V.


Veins carry blood to the heart

Veins enter the heart - look for the e's.


The vena cava and pulmonary vein are both veins

Vena cava, pulmonary vein - look for the e's.


ARTERIES carry blood AWAY from the heart

Look for the a's.


The aorta and pulmonary artery are both arteries

Aorta, pulmonary artery - look for the a's.

True or false? All arteries carry oxygenated blood?

Which vein takes oxygenated blood from the lungs?

Which artery takes deoxygenated blood to the lungs?

The heart, as an organ, needs its own supply of oxygenated blood. Therefore, there are coronary arteries, that branch off the aorta. These coronary arteries surround the heart cells to supply them with oxygen.

It is the case that the heart beats automatically?

Your heart contracting (beating) is not like your arm bending or your legs moving, which you can consciously cause to happen or cause to stop happening.

The heart beats automatically, thanks to pacemaker cells in the right atrium wall. **** They produce electrical impulses that spreads across the heart, which make the heart muscles contract.

Science has developed an artificial pacemaker, which someone can get if their heart rate is irregular. It sits under the skin and has a wire connecting it to the heart. What kind of signals does it send to the heart to make it contract rhythmically?